Dampening fluid cooling and circulating apparatus for lithographic offset press dampening device



H. P. DAHLGREN Nov. 14, 1967 3,352,317 DAMPENING FLUID COOLING ANDCIRCULATING APPARATUS FOR LITHOGRAPHIC OFFSET PRESS DAMPENING DEVICE 2Sheets-Sheet 1 Filed D60. 9, 1964 INVENTOR Harold P Dohlgren ATTORNEYNov. 14, 1967 H p. DAHLGREN 3,3 7

DAMPENING FLUID COOLING AND CIRCULATING APPARATUS FOR LITHOGRAPHICOFFSET PRESS DAMPENING DEVICE 2 Sheets-Shet 2 Filed Dec. 9, 1964 &

Y INVENTOR Harold F? Dohlgren ATTORNEY United States Patent 6 3,352,317DAMPENING FLUID COOLING AND CIRCULAT- ING APPARATUS FOR LITHOGRAPHICOFFSET PRESS DAMPENING DEVICE Harold P. Dahlgren, Dallas, Tex., assignorto Dahlgren Manufacturing Company, Inc., Dallas, Tex., a corporation ofTexas Filed Dec. 9, 1964, Ser. No. 417,183 3 Claims. (Cl. 137--339) Thisinvention is concerned. with the application of dampening fluid to theplate on a lithographic offset printing press and is particularlyconcerned with apparatus for circulating and maintaining a desiredoptimum temperature of the dampening fluid.

In a dampening device for transferring dampening fluid to the plate of alithographic offset printing press it has been customary practice toplace the dampening fluid in a pan or fountain. A pan roller is rotatedthrough the fluid in the fountain to pick up the dampening fluid whichis transferred, either by a ductor roller which oscillates between thepan roller and a transfer roller which in turn runs in contact withdampening rollers running in contact with the plate, or to a speciallyprepared transfer roller, as shown in my co-pending application forpatent, Ser. No. 26,035, now Patent No. 3,168,037, which runs in contactwith an ink form roller to transfer the dampening fluid to the plate.

The dampening fluid usually consists of several chemical compositionsmixed with water, and as disclosed in my said co-pending application,alcohol is mixed with water to provide the dampening fluid.

It has been found that when a new batch of dampening fluid is added tothe fountain same does not readily mix with the dampening fluid therein.The added dampening fluid changes the proportions of the ingredients ofthe dampening fluid, which changes the chemistry thereof, and willtherefore affect the quality of the printing produced by the press untilsuch dampening fluid has become thoroughly mixed, which usually requiresa considerable length of time.

It has also been found that variations in the temperature of thedampening fluid will affect the quality of printmg.

For instance, if the temperature of the dampening fluid solution is toowarm emulsifications of the dampening fluid with ink is increased andthe oxidation of the plate contacted by the dampening fluid isincreased. It ha been found from experience that the temperature of thedampening fluid should not exceed more than about 75 F.

In the type of plate dampening device shown in my said co-pendingapplication, wherein a resilient metering roller, a specially prepared,polished, hydrophilic chrome roller and an ink coated fonn roller arerun in metering relationship, with one of said metering or chromerollers being rotated in the dampening fluid container, it has beenfound that a volatile, watery type of alcohol is a desirable ingredientof the dampening fluid.

If the temperature of the dampening fluid is allowed to rise above acertain maximum, the alcohol will evaporate more rapidly, requiring thereplenishment of the alcohol at more frequent interval and reducing theeffectiveness thereof.

It is, therefore, a primary object of this invention to provide adampening fluid storage and circulation system which diffuses and mixesthe dampening fluid before it reaches the dampening fluid pan so thatthe addition of dampening fluid to the reservoir will not materiallyaffect the mixture and distribution of the elements therein to such anextent that it would affect the quality of the printing.

Another object of the invention is to provide a dampening fluid storageand circulation system wherein the dampening fluid is circulated througha refrigeration unit, to maintain the temperature of the dampening fluidat a predetermined optimum value.

Still another object of the invention is to provide a dampening fluidstorage and circulation system wherein the dampening fluid is drawn backinto the reservoir for the dampening fluid by venturi action supplied bydischarge pressure from the circulating pump, so that the dampeningfluid will flow from the dampening fluid pan back into the reservoireven though the dampening fluid pan is located below the level of theliquid in the reservoir.

Still another object of the invention is to provide a dampening fluidcirculation system wherein the dampen ing fluid is deposited in thedampening fluid pan through a horizontally disposed perforated diffuserpipe, to assure that same is properly mixed and agitated to maintain thechemical diffusion and balance thereof, and wherein the level of fluidin the dampening fluid pan is maintained by a removable drain pipe whichmay be removed to allow the dampening fluid to drain from the pan backinto the reservoir therefor.

Other and further objects of the invention will become apparent uponreading the detailed specification hereinafter following and byreferring to the drawings annexed hereto.

In the drawings: 7

FIGURE I is a partially diagrammatic cross-sectional elevational view ofthe dampening fluid circulating system to which this invention isaddressed;

FIGURE II is an enlarged transverse sectional view of the dampeningfluid fountain showing the diffuser pipe and the removable water leveland drain pipe;

FIGURE III is a front perspective view of the diffuser pipe; and

FIGURE IV is a top perspective view of the dampening fluid fountain,with the diffuser pipe mounted therein.

Numeral references are employed to indicate the various parts shown inthe drawings and like numerals indicate like parts throughout thevarious figures of the drawings.

As shown in FIGURE II the metering roller A has a smooth resilientsurface thereon, which is run in surface pressure relationship to thesurface of the transfer roller B.

Transfer roller B is preferably a smoothly finished, hard surfacedhydrophilic roller such as that disclosed in my aforesaid co-pendingapplication.

The surface of transfer roller B is run in surface pressure'relationshipto the surface of a resilient ink carrying roller C which in turn runsin surface contact with the printing plate E. Ink is supplied to theroller C by a conventional longitudinally oscillating vibrator roller D.The aforesaid rollers and the relationship thereof are as disclosed inmy said co-pending application which is for illustrated purposes only.It will be understood that other types of dampening devices, such asthat wherein the dampening fluid is transferred from the water panroller to the dampening rollers through an oscillating ductor rollercould be employed with the dampening fluid circulating and temperatureregulation device herein disclosed.

A dampening fluid tank or reservoir 1 is provided having heat insulation2 in the walls thereof.

A quantity of dampening fluid 3 is disposed in the reservoir 1. Thedampening fluid 3 may be conventional type of dampening fluid, whichusually consists of a mixture of chemical ingredients and water, or itmay be water and other chemical ingredients mixed with alcohol, as it isused with the dampening device disclosed in my said co-pendingapplication.

The level of the dampening fluid 3 is maintained above the impeller 4 ofthe pump 5. The impeller 4 is rotated through a shaft 6a by an electricmotor 6 mounted on the top of. the reservoir 1. The impeller 4 picks updampening fluid from the container 1 through the intake opening a in thelower wall of the pump housing.

The dampening fluid is forced through the discharge line 7 and is passedthrough a refrigeration unit 8 which has the usual compressor,condenser, receiver, filter and dryer, expansion valve and evaporatorcoils therein. The discharge line 7 is connected to a pipe 9 whichpasses adjacent to the evaporator coil of the refrigeration unit,

and as thedampening fluid passes therethrough, it is cooled. Thetemperature of the refrigeration unit may be maintained by a suitablethermostat control (not shown).

A portion of the refrigerated dampening fluid-is passed from the pipe 9through a hand operated valve 11 and a supply line to the dispenser pipe18 which is disposed in the dampening fluid pan or fountain 15.

A branch line 12 communicates with the upper part of the reservoir 1through a discharge nipple 14. A restrictor nipple 13 is inserted in thebranch line 12, which not only provides for jetting and mixture of thedampening fluid as it is deposited into the reservoir 1, but provides aback pressure on the discharge pipe 7 for the purpose hereinaftermentioned. The fountain supply line 10 is connected to the perforateddispenser pipe 18 by an elbow joint 16 which is in turn connected to a Tjoint 16a to which the separate branches of the dispenser pipe 18 areconnected.

The perforated diffuser pipe 18 extends along the inner wall of thedampening fluid container andhas spaced perforations 19 in thewallthereof through which dampening fluid may be dispensed. The ends ofthe diffuser pipe 18 are closed by removable plugs 18a and 18b wherebythe pipe may be cleanedout.

The diffuser pipe 18 is supported and held down by adjustment screws 21which pass through brackets secured to the inner wall of the fountain15.

A removable drain pipe 22 is seated on a shoulder 24 provided about thepassage 25 leading through the lower wall of the dampening fluidfountain 15. The removable stand pipe 22 maintains the level of thedampening fluid in the pan, indicated at 23. The drainpipe 22 may beremoved to allow the dampening fluid 3 to quickly drain back into thereservoir 1.

A return hose 26 is attached to the outlet drain nipple 25 through whichdampening fluid may return from the pan 15 to the reservoir 1. The'hose26 communicates with a drain back pipe 28 in the reservoir 1 through asuitable nipple 27 passing through the upper wall of the reservoir 1.

The drain back pipe 28 isconnected in communication with a T-fitting 29.

A restrictor nozzle 30 is connected between an outlet from the dischargeconduit 7 and the T-c-oupling 29.

A venturi 32 is connected to an outlet of the T-coupling 29 opposite therestrictor nozzle 30. 'A venturi discharge line 33 isconnected to theopposite end of the venturi 32 and terminates at the bottom of thereservoir 1.

The operation and function of the devicehereinbefore described is asfollows:

The reservoir 1 is filled with suflicient dampening fluid 3 to maintaina level above the pump 5 and the venturi outlet 33.

The dampening fluid may be any known type of dampening fluid, comprisedof a mixture of chemical ingredients and water or a mixture of Water andalcohol, as employed with the dampening device disclosed in my aforesaidco-pending application. 7

The motor 6 is energized to rotate the impeller 4 which forces dampeningfluid through the discharge conduit 7 and pipe 9, passing through therefrigeration unit 8,

where the dampening fluid is maintained to a predetermined maximumtemperature. A portion of dampening fluid is forced through the conduit12 and back to the reservoir 1. A portion of the dampening fluid ispassed through the conduit 10 to the diffuser pipe 18, where it isjetted through the perforations 19- into the dampening fluid pan 15.

It will be observed at this point that the valve 11 may be closed tocause all circulated dampening fluid to pass back to the reservoir 1through the line 12. This is provided so that the temperature of thedampening fluid in the reservoir 1 maybe maintained at a predeterminedmaximum while the dampening device which draws fluid from the supply pan15 is not in operation. Therefore,

when the press is started and the dampener is placed in operation, thedampening fluid .will be at the correct temperature for optimumoperation. It is also desirable that a portion of the dampening fluid becirculated back to the reservoir 1 even when the valve 11 is open, sothat temperature of the dampening fluid in the reservoir 1 may bemaintained at a constant value while the dampener is in operation andwhile the fluid is being circulated through the dampening fluid pan 15.

The dampening fluid is passed through the perforations 19 and depositedin the supply pan 15. The supply pan 15 is filled to a level Where thedampening fluid runs over the overflow drain pipe 22 and back to thesupply reservoir 1 through the hose 26 and drain back conduit 28. It isnoted that the dampening fluid flowing back from the dampening fluidsupply pan 15 passes. through a venturi 32 which lowers the pressure onthe outlet side thereof, thereby creating a suction which draws thedampening fluid from the dampening fluid pan 15.

It will further be observed that flowrestrictors 13 and 10a are placedin the lines 12 and 10 respectively, which with the restrictedperforations 19 in the diffuser pipe 18 cause a back pressure on thefluid discharge line 7 and thereby causes a portion of the fluidsupplied thereto by pump 5 to be jetted through the restricted passage30 di-.

rectly into the venturi 32, thereby increasing the velocity of thefiuid'passing through the venturi 32 and increasing the suction createdacross the venturi. This assures that fluid overflowing. the. drain pipe32 will be drawn back into the reservoir 1 even though the dampenerfluid pan 15 may be situated below the level of the dampening fluid 3 inthe reservoir 1. This is important because in some installations thedampening fluid pan is located below the level of-the dampening fluid 3in the reservoir 1, but nevertheless, the dampening fluid is drawn backinto the dampening fluid reservoir l'from pan 15'by means of the venturi32 in conjunction with restricted jet 30.

Should it be desired to drain the fluid from dampening fluid pan 15 backinto the reservoir 1, such may be quickly done by removing the drainpipe 22, thus allowing the dampening fluid to flow back to the dampeningfluid reservoir 1 through the returnconduits 26 and 28.

By adjusting the opening through-11, the rate of supply of dampeningfluid into the pan 15 may be regulated.

The transfer roller B is rotated in the dampening fluid 23.

in the supply pan 15 and is picked up on the surface there. of andcarried to the nip between the transfer roller B and the resilientmetering roller A.

The transfer roller B is preferably of the type disclosed in myaforesaid co-pending application which has a hard smoothly finishedhydrophilic surface thereon. The pressure relationship between themetering roller A and the transfer roller B may be adjusted to meterfluid between the contacting surfaces thereof and excess dampening fluidwhich does not pass therebetween, flows back into the supply pan 15 bygravity as indicated at 34. Thus, a

regulated supply of dampening fluid is passed between.

the contacting surfaces of the rollers A and B. The metered film ofdampening fluid on the surface of the roller B, is rotated in contactwith an ink carrying resilient roller C and the dampening fluid adheresto the surface of the film of ink on the ink carrying form roller and istransferred to the plate as the roller C rotates in contact therewith.Ink is supplied to the form roller C by an ink supply vibrator roller Dwhich rotates in contact therewith.

It will be understood that this dampening fluid cooling and circulatingdevice and system could be used not only with the types of dampenersshown in my said co-pending application, but could be used withconventional dampeners wherein dampening fluid is transferred to thetransfer roller by a ductor roller and from the transfer roller to theplate through absorbent rnolleton type rollers. It is desirable andadvantageous to maintain the chemical balance of dampening fluid as wellas regulate the temperature of the dampening fluid in the use of suchconventional dampener devices.

Should it be desired to drain the dampening fluid 3 from the reservoir1, same may be done by opening the drain valve 35 attached to drain hose36, which in turn communicates with the reservoir 1 through a nippleextending through the lower wall of the reservoir.

It will be seen that I have provided a dampening fluid cooling andcirculating system, which mixes, difiuses, and maintains the chemicalconsistency of the dampening fluid and regulates the maximum temperaturethereof as it is circulated through the system, and which provides forthe return of the dampening fluid to the reservoir by suction, withoutmechanical force applied for such purpose, even with the dampening fluidsupply pan located below the level of the fluid in the reservoir.

It will be understood that other and further embodiments of my inventionmay be devised without departing from the spirit and scope of theappended claims.

Having described my invention I claim:

1. In a device for circulating dampening fluid in a lithographicprinting press, a reservoir for dampening fluid; a pump disposed belowthe level of fluid in the reservoir; a discharge conduit from the pumpthrough the wall of the reservoir; a refrigeration unit; an elongateddampening fluid container; conduit means connected to the dischargeconduit passing through the refrigeration unit and extending to a pointadjacent the container; a dispersal conduit having spaced perforationsthrough the wall thereof attached to the conduit means and beingdisposed in the container; a return conduit communicating with thecontainer and the reservoir; means to maintain a predetermined level offluid in the container; a venturi connected in the return conduit belowthe level of the fluid in the reservoir; a restricted passage betweenthe discharge conduit and the return conduit, said restricted passagebeing arranged to discharge fluid directly into the entry end of theventuri; and flow restriction means between the pump and the dispersalconduit to cause back pressure in the discharge conduit.

2. The combination called for in claim 1 with the addition of a branchconduit attached in communication with the conduit means after it passesthrough the refrigeration unit and with the reservoir; and valve meansin the conduit means between the branch conduit and the dispersalconduit to permit the dampening fluid to be circulated through thereservoir and refrigeration unit while flow thereof to the dispersalconduit is closed 011 by the valve means.

3. The combination called for in claim 2 with the addition of flowrestriction means in the branch conduit.

References Cited UNITED STATES PATENTS 1,262,707 4/1918 Smith 1013661,969,154 8/1934 Schultz 101148 1,989,375 1/ 1935 Meyercord 101-1772,130,659 9/1938 Wedemeyer 101-366 2,368,500 1/1945 Taylor et a1.101-350 2,604,848 7/1952 Muller 101-147 2,728,690 12/1955 Saeman 101350X 3,045,592 7/1962 Shearer et al 101350 M. CARY NELSON, PrimaryExaminer.

S. SCOTT, Assistant Examiner,

1. A DEVICE FOR CIRCULATING DAMPENING FLUID IN A LITHOGRAPHIC PRINTINGPRESS, A RESERVOIR FOR DAMPENING FLUID; A PUMP DISPOSED BELOW THE LEVELOF FLUID IN THE RESERVOIR; A DISCHARGE CONDUIT FROM THE PUMP THROUGH THEWALL OF THE RESERVOIR; A REFRIGERATION UNIT; AN ELONGATED DAMPENINGFLUID CONTAINER; CONDUIT MEANS CONNECTED TO THE DISCHARGE CONDUITPASSING THROUGH THE REFRIGERATION UNIT AND EXTENDING TO A POINT ADJACENTTHE CONTAINER; A DISPOSAL CONDUIT HAVING SPACED PERFORATIONS THROUGH THEWALL THEREOF ATTACHED TO THE CONDUIT MEANS AND BEING DISPOSED IN THECONTAINER; A RETURN CONDUIT COMMUNICATING WITH THE